As speeds of aircraft continue to increase the requirement of quick decisions and associated executions are mandated in order to maintain safety and preserve lives and property in the crowded skies. The ability to jettison fuel is needed during dire emergency situations such as loss of power during landing and take-off operations to an extent where power to weight ratio is insufficient to maintain flight. Another emergency situation requiring fuel dumping would occur if there were during military action an incendiary weapon in a fuel tank or if there were a wing fire that could not be extinguished. Another is an imminent crash where dumping fuel could prevent fire after crashing. Through the years many devices have been proposed to meet these needs.
For example, U.S. Pat. No. 2,207,724 to Diehl shows a dump valve located in an aircraft fuel compartment coupled with a scoop which directs air into the fuselage, wings and tail assemblies in order to increase pressure in these structures prior to initiating the discharging of fuel. The building up of fuselage, wing and tail pressure prior to and during discharge is required to prevent fuel from entering these confines which are at a reduced pressure to the surrounding environment.
U.S. Pat. No. 2,573,207 to Lipman shows a discharge valve located in an aircraft fuel tank and associated discharge mechanism. The discharge valve and/or discharge mechanism includes all functional and operating parts utilized in the jettison operation in one enclosed device.
U.S. Pat. No. 2,569,172 to Jensen shows a discharge hopper specifically invented to diffuse insecticides or other character of dust from an aircraft. The discharge hopper is lowered from the center section of the aircraft's fuselage and contains agitation mechanism to maintain the proper dispersion of these substances.
U.S. Pat. No. 3,089,677 to Savaria shows a dump valve utilized in an aircraft to discharge chemicals as those used in forest fire assignments. The actuating mechanism is entirely encased and protected from the chemicals to be jettisoned. Included in this invention is a hollow, cylindrical valve, having its interior divided into segments by fin-like radial spokes which tend to dispel turbulence in substances jettisoned.
U.S. Pat. No. 3,096,054 to Ciminagbi shows an interconnected series of separate wing tanks which are normally completely filled and are positioned to receive fuel by gravity from the wing tanks. Fuel is pumped from the intermediate tank to the various engines in such a manner as to avoid any direct communication between the engines and the wing tanks. The intermediate tank is provided with a quick acting discharge valve for dumping the fuel therefrom and from the wing tanks.
U.S. Pat. No. 3,754,601 to Linkewich shows a system for providing loads of retardant slurry on board an aircraft for repeated bombings of a forest fire. The slurry is carried in two drop tanks which have dump doors for direct ejection of the mixture.
U.S. Pat. No. 4,253,626 to Muscatell shows a trap door on the under-side of an airfoil. The door is both part of the under-side of the airfoil and fuel compartment. The trap door is hinged on the forward edge and fastened with a latch on the rear edge of the airfoil. A gasket around the circumference of the trap door mates with the contact surface of the airfoil forming a seal. This trap door swings outward and downward under jettisoning conditions to release stored fuel.
Republic of France Pat. No. 636,411 to Societe d' Emboutissage et de Constructions Mechaniques shows hand actuated valves for use in an aircraft to jettison the contents of fuel and ballast tanks.